A review of flash flood hazards influenced by various solid material sources in mountain environment

Solid material sources, such as sediment, large wood, and vehicles, intensify flash flood hazards. This paper provides a detailed review of processes involving the recruitment, entrainment, transport, and blockage dynamics of various solid material sources. Results indicate that sediment supplied by processes like landslides and debris flows can obstruct river channels, leading to a sudden increase in flash flood levels. The failure of a barrier dam results in an expansion of downstream inundation areas. Large wood and floating vehicles transported by flash floods and debris flows may directly impact and destroy built structures or form blockages at built structures. Blockages lead to a backwater rise, and the sudden amplification of flow during the failure of these blockages causes more severe disasters. Based on these analyses, the paper proposes future research directions primarily focusing on the changes in sediment burial processes caused by the sheltering effects of building groups. Furthermore, the study aims to investigate the flow amplification effects of large wood and vehicle blockage.